Yuri Shirman

A Simple Model of Low-scale Direct Gauge Mediation

We construct a calculable model of low-energy direct gauge mediation making use of the metastable supersymmetry breaking vacua recently discovered by Intriligator, Seiberg and Shih. The standard model gauge group is a subgroup of the global symmetries of the SUSY breaking sector and messengers play an essential role in dynamical SUSY breaking: they are composites of a confining gauge theory, and the holomorphic scalar messenger mass appears as a consequence of the confining dynamics. The SUSY breaking scale is around 100 TeV nevertheless the model is calculable. The minimal non-renormalizable coupling of the Higgs to the DSB sector leads in a simple way to a μ-term, while the B-term arises at two-loop order resulting in a moderately large tan β. A novel feature of this class of models is that some particles from the dynamical SUSY breaking sector may be accessible at the LHC.

Bounds on Unparticles from the Higgs Sector

We study supersymmetric QCD in the conformal window as a laboratory for unparticle physics, and analyze couplings between the unparticle sector and the Higgs sector. These couplings can lead to the unparticle sector being pushed away from its scale invariant fixed point. We show that this implies that low energy experiments will not be able to see unparticle physics, and the best hope of seeing unparticles is in high energy collider experiments such as the Tevatron and the LHC. We also demonstrate how the breaking of scale invariance could be observed at these experiments.

Unparticles: Scales and high energy probes

Unparticles from hidden conformal sectors provide qualitatively new possibilities for physics beyond the standard model. In the theoretical framework of minimal models, we clarify the relation between energy scales entering various phenomenological analyses. We show that these relations always counteract the effective field theory intuition that higher dimension operators are more highly suppressed, and that the requirement of a significant conformal window places strong constraints on possible unparticle signals. With these considerations in mind, we examine some of the most robust and sensitive probes and explore novel effects of unparticles on gauge coupling evolution and fermion production at high energy colliders. These constraints are presented both as bounds on four-fermion interaction scales and as constraints on the fundamental parameter space of minimal models.

Parameter Space of General Gauge Mediation

We study a subspace of General Gauge Mediation (GGM) models which generalize models of gauge mediation. We find superpartner spectra that are markedly different from those of typical gauge and gaugino mediation scenarios. While typical gauge mediation predictions of either a neutralino or stau next-to-lightest supersymmetric particle (NLSP) are easily reproducible with the GGM parameters, chargino and sneutrino NLSPs are generic for many reasonable choices of GGM parameters.

Electroweak Symmetry Breaking from Monopole Condensation

We argue that the electroweak symmetry of the standard model (SM) could be broken via condensation of magnetic monopole bilinears. We present an extension of the SM where this could indeed happen, and where the heavy top mass is also a consequence of the magnetic interactions.

Anomaly Constraints on Monopoles and Dyons

Fermions with magnetic charges can contribute to anomalies. We derive the axial anomaly and gauge anomalies for monopoles and dyons, and nd eight new gauge anomaly cancelation conditions in a general theory with both electric and magnetic charges. As a byproduct we also extend the Zwanziger two-potential formalism to include the parameter, and elaborate on the condition for CP invariance in theories with fermionic dyons.

Odd decays from even anomalies: Gauge mediation signatures without supersymmetry

We analyze the theory and phenomenology of anomalous global chiral symmetries in the presence of an extra dimension. We propose a simple extension of the standard model in 5D whose signatures closely resemble those of supersymmetry with gauge mediation, and we suggest a novel scalar dark matter candidate.

Introduction to Supersymmetry and Supersymmetry Breaking

These lectures, presented at TASI 08 school, provide an introduction to supersymmetry and supersymmetry breaking. We present basic formalism of supersymmetry, supersymmetric non-renormalization theorems, and summarize non-perturbative dynamics of supersymmetric QCD. We then turn to discussion of tree level, non-perturbative, and metastable supersymmetry breaking. We introduce Minimal Supersymmetric Standard Model and discuss soft parameters in the Lagrangian. Finally we discuss several mechanisms for communicating the supersymmetry breaking between the hidden and visible sectors.

Supersymmetry Breaking Triggered by Monopoles

We investigateN = 1 supersymmetric gauge theories where monopole condensation triggers supersymmetry breaking in a metastable vacuum. The low-energy eective theory is an O’Raifeartaigh-like model of the kind investigated recently by Shih where the R-symmetry can be spontaneously broken. We examine several implementations with varying degrees of phenomenological interest.

Pre-ADS superpotential from confined monopoles

A bstractAccording to the standard lore only single monopoles contribute to the superpotential on the Coulomb branch of 3D N=2